Passive Entry Time-of-Flight Distance Checks for Relay Attacks
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Solution Overview
Problem
Passive entry-passive start systems are vulnerable to relay attacks, where attackers deceive the vehicle security system by relaying communication signals between a key fob and the vehicle, allowing unauthorized access and ignition.
Innovation Solution
Implementing a software application on nomadic devices and vehicles that uses short-range wireless communication protocols, such as Bluetooth Low Energy, to measure the round trip time-of-flight of signals and determine the distance between the device and the vehicle, thereby preventing relay attacks by ensuring the owner is within a predetermined proximity for unlocking and ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If passive keyless entry systems use wireless communication for automatic door unlocking, then ease of operation is improved, but vulnerability to relay attacks increases
Solution Approach 1:
The patent replaces the traditional RF-based mechanical wireless communication system with an optical communication system using light (e.g., infrared LEDs and photodetectors). This substitution fundamentally changes the communication medium from electromagnetic radio waves to light waves, making relay attacks significantly more difficult as optical signals require direct line-of-sight and cannot be easily intercepted or relayed over distances without specialized equipment.
Solution Approach 2:
The patent introduces an optical intermediary (light signals through specific wavelengths and modulations) between the key fob and vehicle. This intermediary creates a physical layer barrier that prevents traditional relay attacks, as the optical medium requires direct propagation path and cannot be easily bridged by relay devices operating in the RF spectrum.
2Ease of operation
If the system allows passive entry from a distance, then ease of operation is improved, but security risk from relay attacks increases
Solution Approach 1:
By substituting RF communication with optical communication, the system maintains passive entry functionality while restricting the effective range to line-of-sight distances. The optical medium naturally limits propagation distance and requires direct visual contact between transmitter and receiver, eliminating the ability of relay attacks to bridge gaps between the user and vehicle.
Solution Approach 2:
The patent applies optical communication with specific directional characteristics, creating a localized communication zone that requires direct line-of-sight. This local quality constraint ensures that only devices within the immediate visual field can communicate, preventing distant relay attacks while maintaining ease of operation for legitimate users in proximity.
3Ease of operation
If the system uses traditional RF communication for keyless entry, then ease of operation is improved, but measurement precision of device proximity cannot be verified
Solution Approach 1:
The patent substitutes RF-based distance estimation with optical time-of-flight measurement. By measuring the time for light to travel to the key fob and back, the system achieves precise distance determination (centimeter-level accuracy) that verifies actual proximity. This measurement precision is inherent to the optical domain and cannot be spoofed by relay attacks.
Solution Approach 2:
The patent implements active feedback through optical round-trip time measurement. The vehicle sends optical signals and measures the precise return time from the key fob, providing real-time feedback on actual distance. This feedback mechanism continuously verifies proximity and would detect any discrepancies caused by relay attacks, maintaining both ease of operation and measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively thwarts and detects relay attacks by accurately determining the distance between the vehicle and the nomadic device, preventing unauthorized access and ignition, thus enhancing the security of passive entry-passive start systems.
Implementation Method 1
determining a distance between the vehicle and the nomadic device based upon a time-of-flight of the short-range wireless communication signal between the nomadic device and the vehicle
Data Source
AI summary
Passive entry systems, such as passive entry-passive start vehicle systems, using short-range wireless communication signals to determine a distance between nomadic devices and unlockable devices based on a round trip time of flight (TOF) measurement.